Most of the displays currently used for portable information equipments are monochrome reflective LCDs whose conventional transmissive TN or STN LCD backlight is just replaced by a reflector. However, these reflective LCDs are not appropriate either for color due to not enough brightness or for high resolution because of a parallax caused by the two polarizer-structure.
As discussed above, conventional reflective LCDs is composed of TN-mode or STN-mode with two polarizers and diffusing reflector placed behind the LCD panel. Problems of this type LCD are parallax and low brightness which limits its application in portable high information tools such as hand-held personal computers. To improve these problems, a single-polarizer reflective TFT LCD have been developed, this display composed of a front scattering film, a polarizer, a retardation film, and a TFT LCD panel. A reflective film was formed in the TN LC cell. (AM-LCD'96/IDW'96, P.329-332, FIG. 1) This structure raise the required characteristics of reflective LCDs as follows. Brightness is raised by using one polarizer, and the view angle is increased due to the front scattering film can eliminate the mirror reflection. However, we found that the characteristics of the single-polarizer R-LCD(reflective LCD) were easily influence by the back scattering of the front-scattering-film. Especially, in the color display, the contrast greatly went down and the deterioration of color reproduction was obvious. For example, the contrast ratio of this case is only 6:1.